FIG. 1 represents schematically such a tree-structure network.
A line-termination device 2 is connected by a line 5, for example an optical fiber or a copper line, to a group of network-termination devices 3. Dividers shown under reference number 4, for example optical dividers, may be used for sharing the signals originating from the line-termination device 2 between the network-termination devices 3. The device 2 provides the interface with the rest of the telecommunications network shown under reference number 1, for example the Internet network.
Each network-termination device comprises a modem, making it possible to perform functions such as modulation, demodulation, multiplexing, demultiplexing, etc., depending on the communication protocol used on the line.
The line 5 is shared between several network-termination devices 3. The device 2 may optionally manage the allocation of this shared resource between the devices 3. For example, the devices 3 may each have a timeslot for transmitting messages to the line-termination device 2. It is the device 2 which sends messages to the devices 3 indicating which of these devices is entitled to transmit during a given timeslot. Such a technology is, for example, TDMA (Time Division Multiple Access).
The communications on the line are governed by a protocol, that is to say a set of descriptions of formatting, segmentation and sharing of data between several applications and several network-termination devices.
A communication protocol on the line covers both the format of the payload data interchanged over the line (for example divided into octets or into ATM cells), and the format of the frames interchanged (for example a format defining the frame headers), the type of sharing or multiplexing of the resources (for example WDM, “Wavelength Division Multiplexing”), the communication mode (PMP for example), the nature of the traffic supported (half-duplex, full-duplex, simplex, etc.), etc.
The communications protocol over the line is likely to change. Other access technologies may be used.
For example, in the case of an optical line, the protocol used has evolved changing from a fixed multiplexing of octets (the TPON “Telecommunication over Passive Optical Network” format, and point-to-multipoint passive optical transmission mode according to the ITU-T recommendation G.982 and the ETSI standard ETS.300 463) to a dynamic multiplexing of ATM (“Asynchronous Transfer Mode”) cells in native mode or on an STM1/STM4 “Synchronous Transport Module” (the APON then BPON format, for “ATM-based PON” and “Broadband PON” respectively, and point-to-multipoint passive optical transmission mode based on ATM according to the ITU-T recommendations G.983) or to a native Ethernet multiplexing (the EPON, GEPON or GigE format for “Ethernet PON”, “Gigabit Ethernet PON” and “Gigabit Ethernet”, in point-to-multipoint mode according to an IEEE standard), then finally to a dynamic multiplexing of octets (the GPON, for “Gigabit PON”, protocol).
The protocol governing the communications over the line is naturally still likely to evolve, perhaps according to a format with MPLS “Multi-Protocol Label Switching” encapsulation.
Other service-integration multiplexing formats will probably appear.
It is known practice to replace the network-termination devices 3 in order to carry out these protocol upgrades. However, the use of this solution is complex and costly because of the manufacture of new devices, and of the replacement operations to be arranged for the network terminations. Moreover, such a solution requires an interruption of service while the network-termination device is replaced.
An alternative solution consists in providing each user with a medium of the USB key type storing a program for reconfiguration of a network-termination device. With the latter solution, in the case of point-to-multipoint (or PMP) communications, the modifications affecting a plurality of network-termination devices must be made in a relatively short time period, and simultaneously, so that the communications over the shared line operate correctly.
There is a need for a low-cost solution for the reconfiguration of network-termination devices that is simple to apply and that does not require service interruption.